It is recommended to add acid to water while diluting because the process of dissolving acid in water is highly exothermic, meaning it releases a lot of heat. When acid is added slowly to a large volume of water, the heat is absorbed gradually and dissipated safely. If water is added to concentrated acid instead, the heat is released all at once, causing the mixture to splash and potentially cause burns or break the container due to sudden overheating. This safer method prevents dangerous splashes and accidents during dilution.
Explanation
- Adding acid to water starts with a dilute solution where heat is absorbed gradually.
- Adding water to acid causes rapid heat release, splashing, and risks of burns or glass breakage.
- Gradual mixing with stirring ensures safety and control over temperature changes.
Thus, the safety principle in diluting acids is: always add acid to water, never water to acid.
